We investigated how landscape features influence gene flow
of black bears by testing the relative support for 36 alternative
landscape resistance hypotheses, including isolation by distance
(IBD) in each of 12 study areas in the north central U.S. Rocky
Mountains. The study areas all contained the same basic elements,
but differed in extent of forest fragmentation, altitude, variation
in elevation and road coverage. In all but one of the study areas,
isolation by landscape resistance was more supported than IBD
suggesting gene flow is likely influenced by elevation, forest
cover, and roads. However, the landscape features influencing
gene flow varied among study areas. Using subsets of loci usually
gave models with the very similar landscape features influencing
gene flow as with all loci, suggesting the landscape features
influencing gene flow were correctly identified. To test if the
cause of the variability of supported landscape features in study
areas resulted from landscape differences among study areas,
we conducted a limiting factor analysis. We found that features
were supported in landscape models only when the features were
highly variable. This is perhaps not surprising but suggests
an important cautionary note ­ that if landscape features
are not found to influence gene flow, researchers should not
automatically conclude that the features are unimportant to the
species' movement and gene flow. Failure to investigate multiple
study areas that have a range of variability in landscape features
could cause misleading inferences about which landscape features
generally limit gene flow. This could lead to potentially erroneous
identification of corridors and barriers if models are transferred
between areas with different landscape characteristics.